When soap is dissolved in water, the surface tension

When soap is dissolved in water, the surface tension initially decreases; option [A]. Soap molecules contain hydrophilic heads and hydrophobic tails. The hydrophobic tails disrupt the cohesive forces between water molecules at the surface, reducing surface tension. This decrease facilitates the spreading of water and enhances its ability to wet surfaces, enabling effective cleaning.

However, at higher concentrations of soap, the excess molecules can aggregate to form structures called micelles. In these micelles, the hydrophobic tails are shielded from the water, leading to a slight increase in surface tension compared to the initial decrease. This increase occurs because the micelles effectively reduce the number of free soap molecules available to disrupt the water’s surface tension directly.

Therefore, the behavior of surface tension when soap is dissolved in water can be described as initially decreasing due to the disruptive action of individual soap molecules, followed by a potential slight increase as micelles form at higher concentrations. Overall, the presence of soap alters the surface tension of water, impacting its properties and enhancing its effectiveness in cleaning applications.